Fluoroscopy of Spontaneous Breathing is More Sensitive Than Phrenic Nerve Stimulation for Detection of Right Phrenic Nerve Injury During Cryoballoon Ablation of Atrial Fibrillation

Management of phrenic nerve injury post-cardiac surgery in the paediatric patient

BACKGROUND

Phrenic nerve injury is a common complication of cardiac and thoracic surgical procedures, with potentially severe effects on the health of a child. This review aims to summarise the available literature on the diagnosis and management of PNI post-cardiac surgery in paediatric patients with CHD.

MAIN BODY

The presence of injury post-surgery can be difficult to detect and may present with non-specific symptoms, emphasising the importance of an effective diagnostic strategy. Chest X-ray is usually the first investigation for a suspected diagnosis of PNI, which is usually confirmed using fluoroscopy, ultrasound scan, or phrenic nerve stimulation (gold standard). Management options include supportive ventilation and/or invasive diaphragmatic plication surgery. While the optimal timing of plication surgery remains controversial, it is now the most widely accepted treatment for PNI in children post-CHD surgery, especially for very young patients who cannot be weaned off supportive ventilation. Further research is needed to determine the optimal timing of surgical intervention for positive outcomes and to explore the benefits of using minimally invasive surgical techniques in children.

CONCLUSION

PNI is a common and serious complication of CHD surgery, therefore, its diagnosis and management in the paediatric population are of major importance. Further research is needed to determine the optimal timing of surgical intervention for positive outcomes and to explore the benefits of using minimally invasive surgical techniques in children.

Comparison Between M-Mode Ultrasonography and Fluoroscopy for Diaphragm Excursion Measurement in Patients With Acquired Brain Injury

OBJECTIVES

Patients with acquired brain injury show decreased pulmonary function and diaphragm excursion (DE), which can affect functional outcomes. This study aimed to compare ultrasonography (US) and fluoroscopy for DE assessment and to determine how the relationship between pulmonary function test results and DE differs according to the paralytic condition.

METHODS

From September 2017 to April 2018, we prospectively enrolled patients with acquired brain injury. The patients underwent a pulmonary function test, including the functional vital capacity, forced expiratory volume at 1 second, forced expiratory volume at 1 second-to-functional vital capacity ratio, peak cough flow, and respiratory muscle strength such as the maximal inspiratory pressure and maximal expiratory pressure. Diaphragm excursion was measured with M-mode US and fluoroscopy on admission. A partial correlation analysis was used to assess the correlation between US and fluoroscopy for DE assessment.

RESULTS

During the study period, 50 patients with acquired brain injury were enrolled. After adjusting for age, sex, height, and weight, the correlation coefficients between US and fluoroscopy were 0.744 for the right side (P < .001) and 0.631 for the left side (P < .001). In a subgroup analysis for patients with hemiplegia, the correlation coefficients were 0.507 for the paretic side (P = .007) and 0.677 for the nonparetic side (P < .001). Diaphragm excursion in the nonparetic side was significantly correlated with the maximal inspiratory pressure, maximal expiratory pressure, and peak cough flow (P < .05).

CONCLUSIONS

M-mode US can be an alternative method for DE measurement in patients with impaired locomotion function after acquired brain injury. Preserved function of the nonparetic side might affect pulmonary function after brain injury, which suggests the importance of prestroke respiratory function.

[Catheter ablation of atrial fibrillation : Status quo]

Catheter ablation of atrial fibrillation (AF) is a standard part of treatment with respect to rhythm control. In this article, the authors provide a review of the state-of-the-art knowledge of AF catheter ablation including current indications, possible energy forms, procedural methods and endpoints as well as follow-up and further anticoagulation.

Efficacy and safety of cryoballoon ablation for Chinese patients over 75 years old: A comparison with a younger cohort

INTRODUCTION

Cryoballoon ablation (CBA) results in satisfactory outcomes for drug-resistant atrial fibrillation (AF) patients. However, the efficacy and safety of CBA have not yet been tested in the Chinese elderly population. Therefore, this study compared the recurrence of AF and complications of CBA in patients ≥75 years and <75 years.

METHODS

A total of 677 patients (<75 years, n = 550; ≥ 75 years, n = 127) with paroxysmal (n = 603) or persistent (n = 74) non-valvular drug-resistant AF were included. The efficacy was assessed by the recurrence of AF, and the safety was evaluated by peri- and post-procedural complications.

RESULTS

The CHA2DS2-VASc (2.6 ± 1.7 vs 4.8 ± 1.6, P < .01) and HAS-BLED (1.8 ± 0.8 vs 2.0 ± 0.8, P = .01) scores were significantly higher in the elderly group. The instant pulmonary vein isolation success rate was comparable (99.11% younger vs 98.98% older, P = .99). After a mean follow-up time of 12.8 ± 9.6 months, the 1-year freedom from AF rate was 80.6% vs 85.8% in the older and younger groups, respectively, while the survival analysis showed a nonsignificant difference in the rate of freedom from AF (log-rank P = .46). Cox regression showed that age was not a predictive factor for AF recurrence and was not dichotomized (hazard ratio [HR] = 0.868, 95% confidence interval [CI] 0.509-1.481; P = .6046) or continuous (HR = 0.990, 95% CI, 0.968-1.012, P = .3642). Similar complications rates were observed, including stroke (1.0% younger vs 0.93% older, P = .95) and major hemorrhagic events (1.2% younger vs 0% elder, P = .25).

CONCLUSIONS

The efficacy and safety profiles of CBA in patients older than 75 years are comparable with those in younger patients.

Coronary sinus catheter placement via left cubital vein for phrenic nerve stimulation during pulmonary vein isolation

Phrenic nerve (PN) stimulation is essential for the elimination of PN palsy during balloon-based pulmonary vein isolation (PVI). Although ultrasound-guided vascular access is safe, insertion of a PN stimulation catheter via central venous access carries a potential risk of the development of mechanical complications. We evaluated the safety of a left cubital vein approach for positioning a 20-electrode atrial cardioversion (BeeAT) catheter in the coronary sinus (CS), and the feasibility of right PN pacing from the superior vena cava (SVC) using proximal electrodes of the BeeAT catheter. In total, 106 consecutive patients who underwent balloon-based PVI with a left cubital vein approach for BeeAT catheter positioning were retrospectively assessed. The left cubital approach was successful in 105 patients (99.1%), and catheter insertion into the CS was possible for 104 patients (99.0%). Among these patients, constant right PN pacing from the SVC was obtained for 89 patients (89/104, 85.6%). In five patients, transient loss of right PN capture occurred during right pulmonary vein ablation. No persistent right PN palsy was observed. Small subcutaneous hemorrhage was observed in eight patients (7.5%). Neuropathy, pseudoaneurysm, arteriovenous fistula, and perforations associated with the left cubital approach were not detected. Body mass index was significantly higher in the right PN pacing failure group than in the right PN pacing success group (26.2 ± 3.2 vs. 23.8 ± 3.8; P = 0.025). CS catheter placement with a left cubital vein approach for right PN stimulation was found to be safe and feasible. Right PN pacing from the SVC using a BeeAT catheter was successfully achieved in the majority of the patients. This approach may prove to be preferable for non-obese patients.

Electrical isolation of the superior vena cava by laser balloon ablation in patients with atrial fibrillation

PURPOSE

The aim of the present study is to evaluate the feasibility and safety of SVC electrical isolation by LB ablation in patients with atrial fibrillation (AF) referred for pulmonary vein isolation (PVI).

METHODS

Electrical disconnection of the SVC was attempted by LB in 13 consecutive patients (59 ± 10.5 years, 11 male) with AF following PVI. PVI was successfully achieved by standard LB in all before attempting SVC isolation.

RESULTS

A laser beam was delivered with 6.3 ± 2.3 W and 8.4 ± 2.7 W (P = 0.001) during 5.38 ± 2.4 min and 9.75 ± 1.6 min (P = 0.024) to achieve SVC and PV, respectively. Isolation of the SVC by LB was accomplished in 8 patients (61%) without complications. Phrenic nerve palsy developed in 3 patients (23%), which resulted in early procedure termination before isolation. Technical problems or interposition of a pacemaker lead to prevented SVC isolation in the remaining 2 patients. After a mean follow-up of 19 ± 3 months, no patient recovered from phrenic nerve palsy.

CONCLUSIONS

SVC isolation by LB is feasible but associated with a high risk of phrenic nerve palsy. Limitation of laser delivery time and power appears insufficient to prevent this complication.

Femoral venous pressure waveform as indicator of phrenic nerve injury in the setting of second-generation cryoballoon ablation

AIMS

Femoral venous pressure waveform (VPW) analysis has been recently described as a novel method to assess phrenic nerve function during atrial fibrillation ablation procedures by means of the cryoballoon technique. In this study, we sought to evaluate the feasibility and effectiveness of this technique, with respect to the incidence of phrenic nerve injury (PNI), in comparison with the traditional abdominal palpation technique alone.

METHODS

Consecutive patients undergoing second-generation cryoballoon ablation (CB-A) from June 2014 to June 2015 were retrospectively analyzed. Diagnosis of PNI was made if any reduced motility or paralysis of the hemidiaphragm was detected on fluoroscopy.

RESULTS

During the study period, a total of 350 consecutive patients (man 67%, age 57.2 ± 12.9 years) were enrolled (200 using traditional phrenic nerve assessment and 150 using VPW monitoring). The incidence of PNI in the overall population was 8.0% (28/350); of these, eight were impending PNI (2.3%), 14 transient (4.0%), and six persistent (1.7%). Patients having undergone CB-A with traditional assessment experienced 18 phrenic nerve palsies (9.0%) vs two in 'VPW monitoring' group (1.3%; P = 0.002). Specifically, the former presented 12 transient (6.0%) and six persistent (3.0%) phrenic nerve palsies, and the latter exhibited two transient (1.3%; P = 0.03) and no persistent (0%; P = 0.04) phrenic nerve palsies.

CONCLUSION

In conclusion, this novel method assessing the VPW for predicting PNI is inexpensive, easily available, with reproducible measurements, and appears to be more effective than traditional assessment methods.

Prevalence and clinical outcome of phrenic nerve injury during superior vena cava isolation and circumferential pulmonary vein antrum isolation using radiofrequency energy

BACKGROUND

Phrenic nerve injury (PNI) is recognized as an important complication during atrial fibrillation ablation. This study aimed to investigate the incidence and outcome of PNI during superior vena cava isolation (SVCI) and circumferential pulmonary vein isolation (CPVI) using radiofrequency (RF) energy and the factors associated with its occurrence.

METHODS AND RESULTS

Five hundred sixty-seven consecutive patients who underwent SVCI after CPVI without substrate modification who completed a 12-month follow-up were retrospectively analyzed. Point-by-point RF applications were applied with maximum energy settings of 35 W and 30 seconds for the SVCI. In the former 210 patients, sites where pacing captured the PN were avoided whenever possible; however, the maximum power was 35 W. In the latter 357 patients, RF energy was delivered regardless of PN capture; however, the power at PN capture sites was limited to 10 W during continuous diaphragmatic movement monitoring on fluoroscopy. Circumferential pulmonary vein isolation and SVCI were successfully achieved in all. Twelve patients (2.1%) had PNI during SVCI but not during CPVI. Phrenic nerve injury completely recovered in all patients a median of 8.0 months after the procedure. The prevalence was higher in the former period (3.8% vs 1.1%; P = .03). A multivariate logistic regression analysis revealed that the study period (odds ratio 3.546; 95% CI 1.051-11.965; P = .041) was the sole independent predictor for identifying patients with PNI during SVCI.

CONCLUSIONS

Phrenic nerve injury occurred in 2.1% of the patients. All occurred during SVCI but not during contemporary CPVI. Energy titration and continuous diaphragmatic movement monitoring significantly decreased the incidence during SVCI.